Roads Generate Electricity for Even the Toughest Tasks

09 Jan 2018

"Far too expensive: ridiculous idea." They said that about air travel, the battery electric bus (200,000 and counting) and much else besides and now they are saying it about solar roads.

The new IDTechEx report, "Electrically Smart Roads 2018-2028" puts the record straight. Critics miss economies of scale that are coming and the improvements ahead with different solar power at least doubling its output. They miss the big picture of roads and their environs generating electricity and becoming more multifunctional to solve problems that are hugely expensive and dangerous today like inadequate deicing and electric vehicle charging. Multiple paybacks await.

Closely allied to the opportunity to make road surfaces smart with self-powered, embedded interactive lighting and light-emitting signage, structural health monitoring, sensing and more is the opportunity to have adjoining photovoltaic barriers (trials in Taiwan and the Netherlands) and smart roofing over the road (China and elsewhere). A solar roof on a road will make twice as much electricity per unit area compared to a solar road and be more easily upgraded to affordable higher efficiency PV as it becomes available but it may be considered ugly and not receive planning permission for that reason. South Korea has built a freeway with the median covered by solar panels above a bike path.

Add properly designed wind turbines by the road raised to more effective heights. Maybe add Airborne Wind Energy AWE usually consisting of tethered drones that rise to 200-1000 meters where winds are four times as strong, particularly at night when solar is dead. In 2018 they will be on sale from Kitegen Norway and some companies in the Netherlands initially generating 30-100kW. For safety reasons they will need to be at least a tether length away from the road. Detailed analysis of AWE beyond the consideration given in the smart road report is given in the IDTechEx report, "Airborne Wind Energy AWE 2018-2028".

Taken together, even a few of the electricity generation options compared in report, "Electrically Smart Roads 2018-2028" can provide the off grid megawatts to do truly heroic things like charging electric vehicles as they go along and automated deicing and snow removal without today's deicing poisons entering the soil, air and noise pollution and hundreds of thousands of deaths yearly from winter road conditions. Yes, the cost of ownership of self-powered roads needs to come down, maybe by a factor of five but that problem is trivial to that overcome earlier by air travel, the electric vehicle and the transistor to take just three. Just Bouygues Colas of France claims over 100 solar road projects, half of them abroad. Not a bad beginning in only three years.

Radical new inventions tend to succeed when the marketing goes beyond direct replacements to new capability and Solar Roadways in the USA with integral lighting and signage in their solar road modules is a good example of this. The report notes that Pavegen of the UK harvests motion in its electricity generating paving slabs and they double as sensors but others plan piezoelectric and electrodynamic harvesting of movement of roads caused by traffic.

Roads and adjoining areas are a precious resource. They are capable of much more than carrying traffic from place to place. Indeed, it is already common for them to have utilities piped underneath and multifunctional gantries straddling them for directing and monitoring traffic, advertising and so on but this is only a primitive beginning. KWS, a VolkerWessels company, Wavin and Total are working on the development of "PlasticRoad" - hollow giant road slabs carrying utility cables and pipes and acting as a flood water receptacle. It could be solar. Every component of the PlasticRoad is being designed to make its application completely circular, with the goal of using recycled plastic as much as possible. Obviously thinking has already gone beyond putting these high technology delights under or on conventional road materials.

Raghu Das CEO of IDTechEx advises, "The solar, lighting, signage, sensor etc. road and other surfaces will excel as part of modular concrete or plastic road surface units that are factory assembled. This total rethink of road construction provides opportunities for new materials and specialist machinery. Indeed electrically smart roads and their surroundings have the potential to be a $100 billion business."

The new IDTechEx report, "Electricity Generation by Urban Infrastructure: Zero Emission 2018-2050" reveals that researchers from ETH Zurich have built a prototype of a three millimetre thin, curved concrete solar roof using innovative digital design and fabrication methods based on a polymer fabric frame for the concrete. The system will be used in an actual construction project for the first time in 2018. Maybe it has a place in road bridge design. ETH professor Arno Schlüter is developing a building system with sensors that uses heat at low temperatures to create a pleasant interior climate. For this purpose, he uses components of the structure, including the roof, that are thermally activated, so again multifunctional laminar structures are the name of the game.